Feathering screw propeller



Aug. 6, 1929. H` s. HELE-SHAW ET AL 1,723,617

FEATHERING SCREW PROPELLERS Filed Novr 2, 1925 lll lli

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Patented Aug. .6, 1929.

A UNITED STATES PATENT OFFICE.

may snma HELE-SHAW AND 'rnouas EDWARD einem, or LoNDoN, ENGLAND.

FEATHEBING SCREW -YROPELLER Application med November 1925, Serial No. 66,151, and in Great Britain December ,8, 1924.

This invention relates to featherin propellers particularly for use on aix-cra t.

Asis well known an\essential condition :for the successful operation of an aeroplaneis'that the speed o the engine driving the propeller or air screw should be capable of control and this is eilected according to present practice by the airman operating the throttle valve of the engine.

It is conceivable that there are various ways by which the present hand control could be replaced by an automatic control, such for example as a governor driven b the engine controlling'the throttle, but `there is in a propeller itself a potent means for ensuring a practically constant speed of the engine at its highest power and eiiiciency. Plhis desideratum can be accomplished if means are available for varying the pitch of the propeller or airscrew and many attempts have been made to produce an air screw or propeller of this kindn The .object oil our invention is to provide such propeller orn airscrew in combination with a control mechanism by means of which the pitch oi the propeller or airscrew will, in normal running, be automatically varied, a further object of the invention be ing to provide in addition to the automatic control, a means whereby hand control can he eected in emergencies and a means whereby should the control mechanism fail itor any reason the pitch of the propeller or airscrew will be adjusted or held in a normal or predetermined pitch leaving the pilot ilree to taire over control by his engine throttle rllhe invention consists therefore, in its broadest aspect, of a driving mechanism lor aircraft and the lilie comprising a propeller having its blades capable of movement about axes to vary their pitch, an engine for driving said propeller, mechanism lor altering the pitch of the propeller blades and a governor driven by the engine and operatively connected with the pitch altering mechanism for automatically controlling the pitch of the propeller blades in accordance with the engine speed.

The referred form of the invention in volves t e employment of a hydraulic transmission mechanism comprising a pump controlled in accordance with the engine speed and a ram or rams in liquid circuit with thepump for effecting the desired movement of the propellenbla es about theirv axes.

The invention further includes the provision of emergency means, whereb the cony illustrated in the accompanying drawings wherein Figure 1 is a more or less diagramn matic sectional View of a propeller constructed and controlled in accordance with the invention, Figure 2 isl a plan view illustrating the method of swivelling the propeller blades and Figure Sis a section on theline 3-3 of Figure 1 with parts re moved for clearness of illustration.

Referring to these drawings throughout which like numerals of reference indicate corresponding parts the numerals l and 1l designate the two propeller blades which are mounted in the hub shell 2 so as to be ca pable of rotation about an axis perpendicular to the axis of the hollow driving shaft Si. Each blade is supported in the hub by means of two journal bearings 4 and 5 and a ball thrust 6 is fitted between each blade and the hub in order to sustain the centrifugal force on the blade and render it rotatable about its axis without undue friction. Each blade is rovided with an arm Lending in a cylindrical shalt 8, on which slides aMT piece 9 which is ivoted to the crosshead 10. ln the case o one blade the 'T' piece il is mounted in the crosshead 10 in an eccentric bush 58 which bush is prevented from rotat ing by means of castellations 59 engaging with similar castellations in a washer GU bolted to the crossliead. The crosshead is slidably carried in the hub by means of `two bearings 11 and 12 and is arranged so that the crosshead can slide to and fro along the axis of the shaft. The crosshead is bored internall to form a cylinder -which slides on the piston 13, which is fixed to the hub 2 by means of nut 14. A spring 15 is com'- pressed between two spring cases 16 and 17, which are clamped to the hub 2 by means of end cover 18. At the ends of the springs are fitted two loose washers 19, 20 which lllU the pump case.

en i e i ectively with thelshoulder' 21 anlttgherilsirt) 22 on the end, cover.23 whicli is in 'turn clamped to the crosshead 10 by means of a screw thread on the-end of the crosshead sleeve 24 engailng a screw thread on the crosshead 10. v piston `13 is bored to receive the c lindrical valve 25 this valve beinlg fixed an the piston rotating round it. he cylindrical valve 25 is fitted with three annular ports 26, 27, 28 which cooperate with the passages 29, 30, 31 in the piston. A further passage 32- in the piston is in communication with the annular port 28 by means of the hole 33. Three concentric pipes 34, 35, 36, are connected to the valve 25, and the annular port 26 communicates with the pipe 34 by means of the passage 37; the annular port 27 communicates with the annular space between pipes 34, 35 by means of passage 38; and' the annular port 28 communicates with the annular passage between pipes 35, 36 by means of passage 39. The tubular member 40 is provided with projections 41 which pass through holes in the hub 2, and are attached to the crosshead 10 by means of pins 42. The tubular member 40 is attached to the indicator sleeve 43 by means of the ball race 44. The three pipes 34, 35, 36 are attached by means of the unions 45 to three pipes 46, 47, 48 arranged so that the pipe 46 is in communicationl with pipe 34, 47 with the'annular space between 34 and 35, and 48 with the annular space between 35 and 36. Pipes 46, 47 communicate -with the flow and returnoutlets to the variable and reversiblestroke pump 49 arranged to be driven by the en ine and are 'each fitted with a non-return va ve 50l and 501 respectively communicating with the interior space of Pipe 49 communicatesdirectly with the pump case. 51 is a governor driven by the engine 'which operates the l stroke shiftin spindle 52, of the pump through the oatlng lever 53, one end of which is attached to the control crank 54. 56 is a pipe which places' an overhead liquid tank 57 in communication with the case of the variable stroke pump 49. This pump may conveniently be a Hele-Shaw pump of the type described in the specification of lBritish Letters Patent No. 9402 of 1910 but control spindle 52 4of ,the variable stroke pump causing it to pump liquid-preferably oil-out of the pipe 46 into the pipe 47 creating pressure in the latter and causing the cross ead to move to the right. The

crosshead carries with it'the T ieces 9 at- -tached to the Shanks 8 which tinn the two e interior of the` r -for aircrailt) in which durin blades and so causes them to their pitch. On the'othet hand should the speed of the engine fallbelow-thepredetermined point the gtroke'conthrol 52 is moved to the o ite irecton,t e -um 'pum s pressiliirsliquid into the pip? Milind mldves the crosshead 10 in the o posite direction and so changes the'pitch o the blades. Should,

for any reason, the crosshead be driven by y crank 54 operating on the oating lever 53 and so altering the relationship between the movement of the overnor sleeve 55 and the neutral position o the variable stroke pump. In the unlikely event of a pipe breakage or failure of the oil pressure system from any cause the spring 15 will operate so as to .return the blades to a predetermined pitch.

If the ciosshead has moved to a position te the left of that shown in Figure 1 the spring would return it to the position shown in Figure 1 by pressin against the shoulder 21 while if the cross ead has moved to the right the spring would similarly return it by pressing against the nut 22.

The system is kept full of liquid by means of a pipe 56 communicatin to a store of liquid in an overhead tank 5 and any leakage of oil which may take place is returned to the pipe system through one of the nonreturn valves 50l and 50 1n accordance with known ractice. One blade may be rotated relatively to the other in order that the itch of the two blades may be adjusted to lie exactly equal by rotating the eccentric 58.

It will be understood that a suitably indicating device may be provided to inform the pilot at all times of the pitch adopted by. the propeller blades.

It will thus be seen that we have by our invention ovided a driving mechanism normal running the pitch of the pro el er blades will be automatically adjusted rom time to time in accordance with varying conditions while at the same time leaving ito en to the pilot to directly control the pitch y hand should emergency demand it and moreoveriin the event of failure of the mechanism the ropeller blades will adopt a predetermined pitch and the pilot can contro by means of aol prising, a propeller having blades adapted to swivel to vary their ltch, a motor to drive said propeller, hy raulic mechanism associated with the propeller for varying the pitch of its blades, a hydraulic pump communicating with said hydraulic mechanism, a governor being associated with the hydraulic pump whereby output of the compresser is controlled in direct relation to the engine speed, and manually adjustable means for varying the output of the pump relative to the governor.

2..Driving mechanism for aircraft comprising, a propeller having blades adapted to swivel to vary -their pitch, a motor to drive said propeller, hydraulic mechanism associated with the propeller for varying the pitch of its blades, a hydraulic pump communicating with said dydraulic mechanism, a governor driven by the motor which drives the propeller, and means for controlling the output of said pump, said means being adapted to be actuated eit-her manually or by said governor.

3. Driving mechanism for aircraft comprising, a propeller having blades adapted to swivel to vary their itch, a motor to drive said propeller, hy raulic mechanism associated with the propeller for varying the pitch of its blades, al hydraulic pump communicating with said hydraulic mechanism, a governor actuated byy the mot'or which drives the propeller, and means 'associated with the pump for governing its output, said means including a link which may be either manually actuated or actuated by said governor.

4. A variable pitch propeller having blades adapted to swivel to vary their itch, spring means associated with the bla es to yieldably retain or move them to normal position, and means for moving the blades in either direction from normal against tension of said spring.

5. A variable pitch propeller having blades adaptedl to swivel to vary their pitch, hydraulic means associated with the blades for swiveling them in either direction from normal, a source of hydraulic pressure, a return pipe adapted to return the fluid to the source of pressure, and means moved to communicate said hydraulic means with said return pipe by movement of the blades to either of its extreme positions.

6. Driving mechanlsm for aircraft and the like comprising a propeller having its blades capable of swivelling movement about axes to vary their pitch, an engine for driving said propeller, a hydraulic system of transmission to effect the movement of said blades about their axes, a governor mechanism driven by the engine and operating to control the hydraulic transmission mechanism and as a consequence the pitch of the blades in relation to the engine speed and means for restorin the pitch of the blades to a normal pitc on failure of the hydraulic mechanism.

7. Driving mechanism for aircraft comprising a propeller'having its blades capable of swivelling movement about axes to vary their pitch, an engine for driving said propellers, a hydraulic ram connected to the blades to effect the movement of said blades about their axes, a variable stroke pump operating to deliver liquid-to operate said rams and means for controllin the stroke of the pump and consequent y the ram movements.

8. Driving mechanism for aircraft comprising a propeller having blades adapted to swivel to vary their pitch, spring means tending to hold said blades in normal position and compressible upon swivelling of the blades in either direction from normal position, and hydraulic means associated with said pro eller and acting against the tension of said s ring to vary the pitch of the blades in eit er direction from normal, said spring tending to turn and hold the blades in normal position upon failure of the hydraulic means.

In witness whereof we aix our signatures.

HENRY SELBY HELE-SHAW. THOMAS EDWARD BEACHAM. 

